This invention relates generally to an apparatus for applying sealant to the threads of articles, such as fasteners, pipes, particularly to such an apparatus capable of pressing the sealant into the thread roots of the coated articles to completely fill the area where most leaks occur when used in a wide variety of applications.
Sealants of various types are available as preapplied coatings for locking and sealing together threaded parts. One such family of sealants or adhesives is dry to the touch and contains microcapsules of liquid anaerobic (curing in the absence of air) adhesive. During installation of a threaded article coated with this structural adhesive, liquid resin is released from its protective capsule to quickly fill the voids between the mating threads. Upon curing, a tough adhesive bond is formed between the male and female elements. The assembly is thus securely locked and sealed, or "unitized." These and other types of adhesives can be preapplied to parts long before they are used. If properly applied, the particular sealant blocks leakages in threaded joints which can be loosened, tightened and retightened without affecting the seal, and the sealant and can be reused several times on joints without recoating.
Such preapplied sealant and adhesive coatings have been applied on-the-job by manually brushing, dipping, spraying, swabbing, or roll coating, all of which are time consuming, messy and ineffective in assuring that the coating material is sufficiently pressed into the thread roots to provide a consistent leak-proof coating of the threaded parts. If voids or bubbles occur at the thread roots during coating application, leakages are apt to occur through the locked and sealed joint.